Why is he doing this?

I broke up with my ex boyfriend almost 2 months ago, I'm 19wkd pregnant with his kid. I tried to work things out but he said we will never get back together, so I accepted that and haven't really been in contact with him, I saw him in person to get my apt key, and it seems like after that he has been different. He snapped me a pic of himself and liked my picon Instagram. I haven't responded to either just because I don't want to get ahead of myself and get hurt. Is this nothing?